After returning home from school, Tokiko Kurosu finds her foster father dead on the floor, seemingly having tripped and fallen onto the corner of a table. However, Tokiko seems to be utterly unaffected by his death.

The entire Kurosu family gathers at the hospital to mourn, where they encounter police officers Koga and Yashiro, who wish to ask a few questions about the incident. Although initially defensive toward the police, the family begins to point fingers at Tokiko after another family member is killed.

Apparently, many accidental deaths have occurred around Tokiko—starting from before she was adopted. Given her unfazed demeanor when faced with the deaths of those around her, Tokiko appears even more suspicious. While Koga and Yashiro are convinced that these deaths are coincidental, the ceaseless killings surrounding Tokiko lead the remaining members of the Kurosu family to take matters into their own hands.